The Harmon laboratory studies how plants integrate external and internal signals to match metabolism, growth, and development with events occurring in the environment. This project investigates the role the gigantea (gi) gene has in connecting light, phytohormone, and circadian clock signals to regulation of growth and development in Sorghum bicolor (sorghum). Sorghum is a stress tolerant grass plant that is a staple crop in many parts of the world, a forage crop, and a biofuel feedstock. We recently discovered that sorghum plants with a mutation in the gi gene exhibit less growth and later flowering than nonmutant plants. We are interested in discovering the underlying molecular causes of these phenotypes. This project tests the hypothesis that sorghum plants require the gi gene to correctly integrate signals from cryptochrome blue light photoreceptors, the phytohormone gibberellin, and the circadian clock. This project will use a series of light and phytohormone treatments to dissect the signaling pathways requiring the gi gene. In addition, this project characterizes a newly identified cryptochrome 2 (cry2) mutant to investigate connections between blue light signaling- and gibberellin-mediated control of growth and flowering time. The insight into gi and cry2 gene function obtained in this project will provide fundamental insights into the signaling networks grass plants utilize to adjust growth and development in accordance with environmental conditions.
The undergraduate researcher will evaluate growth and flowering time of mutant and nonmutant plants treated with defined light and/or phytohormone regimes. The phenotypes of the uncharacterized cry2 mutant will be compared to the gi mutant under the same treatments. The expression of genes related to gibberellin metabolism, flowering time, and circadian clock function will be determined to determine whether each mutant/environment combination alters the activity of important regulatory pathways. The student will work to combine the gi and cry2 mutations for genetic epistasis tests. Participants will learn widely used molecular biology techniques, including polymerase chain reaction (PCR) and DNA/RNA preparation.
Students should be reliable, diligent, highly motivated, and interested in learning about scientific inquiry. Seeking students with 3.0 GPA or higher that are biological science majors. Molecular biology experience is helpful but not necessary, as we will train students to perform the necessary tasks. The ideal applicant will be available for ~9 hours a week and have a schedule with large blocks of time (~3 hours) to get back and forth to the lab and to have the time to perform experiments.